Automatic fluid flow control for pressure actuated devices

ABSTRACT

An automatic fluid flow control for pressure actuated devices comprising means for automatically maintaining selected predetermined speeds of operation in response to variations in back pressure produced in the control by varying loads imposed on the work to which the control is operatively connected. The control is installed in a pressure fluid condiut between a fluid source and the work to be actuated thereby. It comprises a housing having a back pressure chamber communicating with the pressure actuated work, a tubular fluid intake member movable in axial directions provided with an opening communicating with the back pressure chamber, a piston and sleeve slidably mounted on the intake member covering the opening to varying degrees, an adjustment member for adjusting the position of the intake member in the housing, and a spring bearing on the adjustment member and the piston, whereby variations in load imposed on the work produce back pressure in the chamber and automatic movement of the piston and sleeve to vary the size of the opening and passage of pressure fluid therethrough to the work to maintain uniform selected predetermined speed of operation of the work.

United States Patent [1 1 Moore 1 Oct. 2, 1973 AUTOMATIC FLUID FLOWCONTROL FOR PRESSURE ACTUATED DEVICES [76] Inventor: Robert M. Moore,4695 S. Jason St.,

Englewood, Colo. 80110 [22] Filed: July 26, 1972 [21] Appl. No.: 275,226

Primary Examiner-Henry T. Klinksiek Assistant ExaminerRobert J. MillerArtorneyBertha L. MacGregor [57] ABSTRACT An automatic fluid flowcontrol for pressure actuated devices comprising means for automaticallymaintaining selected predetermined speeds of operation in response tovariations in back pressure produced in the control by varying loadsimposed on the work to which the control is operatively connected. Thecontrol is installed in a pressure fluid condiut between a fluid sourceand the work to be actuated thereby. It comprises a housing having aback pressure chamber communicating with the pressure actuated work, atubular fluid intake member movable in axial directions provided with anopening communicating with the back pressure chamber, a piston andsleeve slidably mounted on the intake member covering the opening tovarying degrees, an adjustment member for adjusting the position of theintake member in the housing, and a spring bearing on the adjustmentmember and the piston, whereby variations in load imposed on the workproduce back pressure in the chamber and automatic movement of thepiston and sleeve to vary the size of the opening and passage ofpressure fluid therethrough to the work to maintain uniform selectedpredetermined speed of operation of the work.

7 Claims, 2 Drawing Figures AUTOMATIC FLUID FLOW CONTROL FOR PRESSUREACTUATEI) DEVICES This invention relates to an automatic flow controldevice which is self contained and designed to be installed in a fluidconduit which conducts pressurized fluid from a source to a tool to beoperated thereby. The fluid control device functions automatically tomaintain selected predetermined speeds of operation in response tovariations in back pressure caused by varying loads imposed on the toolor other fluid operated mechanism, to which the control device isoperatively connected.

The main object of the invention is to control fluid pressure and volumeinput to a tool head or mechanism to maintain predeterminedsubstantially uniform pressure on the tool or mechanism. I-Ieretoforecompressed air or other fluid has been fed from a source into a conduitand conveyed directly to a tool or mechanism for rotating the tool headat a selected speed, but if the load on the tool or mechanism varies,the rotary speed of the tool also varies. By the use of the automaticflow control device of this invention, back pressure in the deviceresulting from increased load on the tool functions automatically toincrease the fluid flow input to the tool to the degree required formaintaining the selected predetermined speed of operation. The absenceof back pressure in the device during periods of normal predeterminedspeed of operation functions automatically to maintain the initiallyselected speed. For example, a fluid cylinder actuated ram, encounteringincreased weights in the course of its travel, causes increased backpressure in the device of this invention and thereby causes increasedenergy input to the ram as required by the increased load thereon.

When embodied in a fluid powered grinder, rated to run at 20,000RPM, ahigh speed which would burn the material being ground, the automaticfluid control device functions to maintain a slower speed withsufficient power to performthe grinding operation.

For the purpose of driving fasteners such as screws and nuts, anautomatic start fluid powered driver is desirable. The automatic controldevice of my invention, used in conjunction with a positive drive screwdriver, will make such a screw dirver an automatic start driver. Thescrew drivertool will run at idle'until power is required, at which timeit will automatically develop predetermined power and set the fastenersuch as a screw or nut, and when removed from the'fastener the tool willassume idle speed.

The automatic fluid control device may be used to maintain uniformpressures on separate means such as air pads used to support testvehicles where different weights may be imposed on the separate pads.

The device has many applications in the fluid power industry which makepresent equipment more versatile, and new equipment less expense toproduce as well as more versatile. In order to obtain the automatic flowcontrol most suitable for anygiven situation, several variables may beadopted, such as piston diameters, spring tension, orifice or orificesconfigurations, in-line pressure and input line CFM or flow.

In the drawing:

FIG. 1 is a horizontal sectional view, partly in elevation, of anautomatic fluid control device embodying my invention, showing the partsin the. positons they assume when no back pressure exists in the device.

FIG. 2 is a horizontal sectional view, partly in elevation, showing thedevice turned from the FIG. 1 position, and showing the parts in thepositions they assume when back pressure exists in the device.

In the embodiment of the invention shown in the drawings, a housing 10comprises a hollow cylindrical body 11 with integral end 12 providedwith a central threaded opening 13 for reception of a threaded coupling14 communicating with a chamber 15 in the housing 10 and a conduit 16leading to a fluid actuated tool or other mechanism (not shown) to becontrolled by the device of this invention. The opposite end of thehousing body 11 is open and internally threaded at 17 adjacent the edgeof the open end.

The automatic control parts mounted in the housing 10 comprise a fluidintake member 20, tubular in form and internally threaded at 21 forreception of a threaded coupling 22 connected to an air or other fluidconduit 23 which conveys pressurized fluid to the intake member 20. Themember 20 is externally threaded as indicated at 24 throughout itslarger diameter portion, and is integral with a smaller diameter tubularportion 25. The inner diameter of the fluid intake member 20 is largerthan the inner diameter of the portion 25 as shown in FIG. 1 at thejunction 26 of the two bores. The end 27 of the fluid intake memberportion 25 is closed. A dowel pin 28 extends through the member 25adjacent the closed end 27 and projects slightly outwardly at oppositeends beyond the said portion 25.

A triangularly shaped opening 30 is provided in the fluid intake memberportion 25"located so that its apex 31 is in a plane adjacent the pin28, and is always exposed to allow passage of fluid regardless of thepositon of a piston about to be described. The shape of the opening 30may be varied as hereinafter explained.

A piston 35 and an integral sleeve 36 are slidably mounted on the fluidintake member 25. Piston rings 37 of any suitable material providesealing contact with the inner surface of the housing body 11. O-rings38 are located between the piston 35 and air intake 25. Movement of thepiston and sleeve in one direction is limited by the pin 28 and in theother direction by a spring 39 that surrounds portions of the intakemembers 25 and 20 and bears at one end on the piston 35 and at the otherend on a threaded adjustment member or washer 40.

The washer 40 is threaded on its inner surface 41 to engage the threadedsurface of the intake member 20, and is threaded on its outer surface 42to engage the internally threaded portion of the housing body 11. Thusthe washer 40 serves as means for adjusting the position of the intakemember 20-25 relatively to the washer and housing. This adjustment ofthe intake member is made to vary the spring pressure in accordance withthe reqirements of the work to be performed. A lock nut 45 threadedlyengages the member 20as indicated at 46, and bears against the washer 40to lock the intake member in adjusted position for the particular workto be performed.

A vent 47 in the housing body 11 provides communication with theatmosphere.

The operaton of the device is as follows:

The fluid intake member 20-25 is mounted in the housing 10 in selectedposition by adjustment of the intake member relatively to the washer 40threadingly engaging the member 20 and the threaded end of the housingbody 11, and locked by the nut 45, according to the chamber 15 andcauses the piston to move to the right of its FIG. 1 position, therebyexposing increasing areas of the opening 30, to quickly automaticallyincrease the input of pressurized fluid into the chamber 15 for passageto the work and thus to maintain uniform energy output to the work, andautomatic return to the predetermined selected speed when the load isagain lessened.

The triangular shape of the opening 30 is well suited to the carryingout of the intended functions of this device, but obviously the form ofthe opening may be modified to provide varying degrees of fluid input tothe chamber depending on the work loads imposed on the tool or mechanismperforming the work. When the triangular form of opening 30 is used, theapex 31 provides a small bleeder opening for the limited fluid intakerequired to maintain relative pressures, and the larger opening 30quickly produced by small movement of the piston and its sleeve underinfluence of back pressure, automatically and instantaneously providesthe increased fluid intake needed to maintain uniform speed of operationof the tool or mechanism controlled by the device.

The small bleeder opening 31 may be separate from the opening 30; forexample, it may be a small vent in the closed top 27 of the intakeportion 25 or in the tubular wall of the portion 25 near its top 27. Theopening 30 may be rectangular or other shape to permit quick passage ofpressure fluid through the back pressure chamber to the work whenincreased back pressure (caused by increased load on the work) forcesthe piston and sleeve to the right of FIG. 1 against the spring 39, andexposes varying areas of the opening 30.

I claim:

1. An automatic fluid flow control for pressure actuated work formaintaining uniform selected predetermined speed of operation of thework under varying load conditions comprising a. a housing having a backpressure chamber therein communicating with the work to be actuated bythe controlled fluid flow,

b. a tubular fluid intake member movable in axial directions relativelyto the housing mounted in the housing in communication with a pressurefluid source,

c. an opening in the intake membcr permitting passage of fluid from theintake member to the back pressure chamber,

d. a piston and sleeve slidably mounted on the intake member and movableto positions wherein the sleeve covers variable areas of the opening,

e. an adjustment member mounted in the housing and engaging the intakemember for initial adjustment of the position of the intake member, and

f. a coiled spring surrounding the intake member and bearing at one endon the piston and at the other end on the adjustment member,

whereby variations in the predetermined work load produce variations inback pressure in the back pressure chamber and cause movement of thepiston and sleeve to vary the size of the opening in the intake memberand consequent passage of pressure fluid therethrough to maintain theselected predetermined speed of operation of the work.

2. The control defined by claim 1, in which the opening in the fluidintake member is triangular in shape, with its apex removed from thepiston and sleeve.

3. The control defined by claim 1, in which the fluid intake member isprovided with a bleeder opening which permits restricted passage offluid from the intake member to the back pressure chamber when there isno back pressure in the chamber, and with a larger opening which permitsquickly increased passage of fluid from the intake member to the backpressure chamber when the piston and sleeve are moved by increased backpressure.

4. The control defined by claim I, in which the housing is provided withan open end and threads on its inner surface adjacent said end, and inwhich the adjustment member is a washer having a central threadedopening engaging the intake member and having threads on its peripherywhich engage the threads on the housing.

5. The control defined by claim 1, in which the fluid intake member isthreaded on its outer surface for reception of a coupling to a pressurefluid source, and for engaging the threaded washer.

6. The control defined by claim 1, in which the fluid intake member hasa central bore larger at the portion connected to the pressure fluidsource.

7. The control defined by claim 1, which includes a lock nut threaded onthe intake member and bearing against the adjustment member to retainthe intake member in its initially adjusted position.

1. An automatic fluid flow control for pressure actuated work formaintaining uniform selected predetermined speed of operation of thework under varying load conditions comprising a. a housing having a backpressure chamber therein communicating with the work to be actuated bythe controlled fluid flow, b. a tubular fluid intake member movable inaxial directions relatively to the housing mounted in the housing incommunication with a pressure fluid source, c. an opening in the intakemember permitting passage of fluid from the intake member to the backpressure chamber, d. a piston and sleeve slidably mounted on the intakemember and movable to positions wherein the sleeve covers variable areasof the opening, e. an adjustment member mounted in the housing andengaging the intake member for initial adjustment of the position of theintake member, and f. a coiled spring surrounding the intake member andbearing at one end on the piston and at the other end on the adjustmentmember, whereby variations in the predetermined work load producevariations in back pressure in the back pressure chamber and causemovement of the piston and sleeve to vary the size of the opening in theintake member and consequent passage of pressure fluid therethrough tomaintain the selected predetermined speed of operation of the work. 2.The control defined by Claim 1, in which the opening in the fluid intakemember is triangular in shape, with its apex removed from the piston andsleeve.
 3. The control defined by claim 1, in which the fluid intakemember is provided with a bleeder opening which permits restrictedpassage of fluid from the intake member to the back pressure chamberwhen there is no back pressure in the chamber, and with a larger openingwhich permits quickly increased passage of fluid from the intake memberto the back pressure chamber when the piston and sleeve are moved byincreased back pressure.
 4. The control defined by claim 1, in which thehousing is provided with an open end and threads on its inner surfaceadjacent said end, and in which the adjustment member is a washer havinga central threaded opening engaging the intake member and having threadson its periphery which engage the threads on the housing.
 5. The controldefined by claim 1, in which the fluid intake member is threaded on itsouter surface for reception of a coupling to a pressure fluid source,and for engaging the threaded washer.
 6. The control defined by claim 1,in which the fluid intake member has a central bore larger at theportion connected to the pressure fluid source.
 7. The control definedby claim 1, which includes a lock nut threaded on the intake member andbearing against the adjustment member to retain the intake member in itsinitially adjusted position.